<button class="exs-first"  lv-button (click)="open()">Click</button>

<ng-template #firstTpl>
  <ul>
    <li class="exs-second" (click)="open2()">Click to open second-level modal</li>
    <li>This is first-level modal</li>
    <li>This is first-level modal</li>
    <li>This is first-level modal</li>
    <li>This is first-level modal</li>
    <li>This is first-level modal</li>
  </ul>
</ng-template>
<ng-template #secondTpl>
  <ul>
    <li class="exs-third" (click)="open3()">Click to open third-level modal</li>
    <li>This is second-level modal</li>
    <li>This is second-level modal</li>
    <li>This is second-level modal</li>
    <li>This is second-level modal</li>
    <li>This is second-level modal</li>
  </ul>
</ng-template>
<ng-template #thirdTpl>
  <ul>
    <li>This is third-level modal</li>
    <li>This is third-level modal</li>
    <li>This is third-level modal</li>
    <li>This is third-level modal</li>
    <li>This is third-level modal</li>
    <li>This is third-level modal</li>
  </ul>
</ng-template>
